Experts chart recycling route

Clean green . . . recycled water is used to water a lawn in Newington. Irrigation at the property now occurs only after dark. Photo: Nick Moir

The Premier, Bob Carr, has met international experts to discuss a large-scale water recycling operation to help solve Sydney's future water needs.

So far Sydney's only water recycling projects are experimental, with the Rouse Hill development in the city's north-west using highly treated waste water for uses such as toilet flushing and outdoor purposes.

But Mr Carr, who has said the existing mandatory water restrictions could become a permanent way of life for Sydney, is being urged to consider more radical solutions to the water shortage.

Mr Carr has met Harry Seah, the deputy director of Singapore's Water Reclamation Department, which substitutes traditional water stores with high-quality recycled water to top up the island's potable supplies.

Mr Seah, who addressed a conference on water use at the University of NSW yesterday, took part in a four-year program to ensure recycled water met guidelines set by the World Health Organisation.

A group of South African investors is hoping to build a $1 billion plant to recycle Sydney's sewage. The company, Services Sydney, wants to "mine" effluent from the southern sewerage system, process it and re-use it to boost river flows as well as for industrial and other uses.

However, environmentalists are sceptical of large engineering solutions to the water shortage, saying the energy it would take to reuse the water would significantly contribute to Sydney's greenhouse gas emissions.

Instead, they say householders and businesses should learn to make do with less.

At Rouse Hill, sewage is piped to a recycling water plant, where it is treated and returned to homes in a separate pipeline. All homes in the area have two water systems - one for drinking water and the other a recycled water system. The recycled water is not for drinking. Stormwater is not included in the project.

In Europe, sewage is recycled back into drinking water, but academics say it would be hard to convince Australians of the safety of such a scheme.

Another barrier to the wide-scale introduction of recycled water is the cost. Its price is likely to be much higher than the relatively modest price Sydney pays for its water - 98 cents for every 100 litres at present.

However, a study commissioned by Melbourne Water found that prices of recycled and traditional water could soon become comparable.

The study - released at the conference yesterday - suggests that the price of recycled water will drop as the technology becomes more widely available.

Mr Carr believes English-style gardens and lawns are unsustainable in Australia's climate and should be replaced with carefully chosen natives.

It was a strategy successfully employed in his own backyard, he said yesterday. "At the back we've got a garden that is being reclaimed by natives - not through deliberate policy, but through total neglect," he said.